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CLINICAL BACTERIOLOGY Flashcards

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1
Q
  1. Each of the statements about the classification of streptococci is
    correct EXCEPT:
    (A) Pneumococci (Streptococcus pneumoniae) are α-hemolytic
    and can be serotyped on the basis of their polysaccharide
    capsules.
    (B) Enterococci are group D streptococci and can be classified by
    their ability to grow in 6.5% sodium chloride.
    (C) Although pneumococci and the viridans streptococci are
    α-hemolytic, they can be differentiated by the bile solubility
    test and their susceptibility to optochin.
    (D) Viridans streptococci are identified by Lancefield grouping,
    which is based on the C carbohydrate in the cell wall.
A

(D) Viridans streptococci are identified by Lancefield grouping,

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2
Q 
54. Each of the following agents is a recognized cause of diarrhea 
EXCEPT:
(A) Clostridium perfringens
(B) Enterococcus faecalis
(C) Escherichia coli
(D) Vibrio cholerae
A

(B) Enterococcus faecalis

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3
Q 
55. Each of the following organisms is an important cause of urinary tract infections EXCEPT:
(A) Escherichia coli
(B) Proteus mirabilis
(C) Klebsiella pneumoniae
(D) Bacteroides fragilis
A

(D) Bacteroides fragilis

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4
Q
  1. Your patient is a 30-year-old woman with nonbloody diarrhea
    for the past 14 hours. Which one of the following organisms is
    LEAST likely to cause this illness?
    (A) Clostridium difficile
    (B) Streptococcus pyogenes
    (C) Shigella dysenteriae
    (D) Salmonella enteritidis
A

(B) Streptococcus pyogenes

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5
Q
  1. Each of the following statements concerning Mycobacterium
    tuberculosis is correct EXCEPT:
    (A) After being stained with carbolfuchsin, M. tuberculosis resists
    decolorization with acid alcohol.
    (B) Mycobacterium tuberculosis has a large amount of mycolic
    acid in its cell wall.
    (C) Mycobacterium tuberculosis appears as a red rod in Gramstained specimens.
    (D) Mycobacterium tuberculosis appears as a red rod in acid-fast–
    stained specimens
A

(C) Mycobacterium tuberculosis appears as a red rod in Gram stained specimens.

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6
Q 
59. Which one of the following diseases is BEST diagnosed by serologic means?
(A) Q fever
(B) Pulmonary tuberculosis
(C) Gonorrhea
(D) Actinomycosis
A

(A) Q fever

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7
Q
  1. Your patient has subacute bacterial endocarditis caused by a
    member of the viridans group of streptococci. Which one of the
    following sites is MOST likely to be the source of the organism?
    (A) Skin
    (B) Colon
    (C) Oropharynx
    (D) Urethra
A

(C) Oropharynx

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8
Q
  1. A culture of skin lesions from a patient with pyoderma (impetigo)
    shows numerous colonies surrounded by a zone of β-hemolysis
    on a blood agar plate. A Gram-stained smear shows gram-positive cocci. If you found the catalase test to be negative, which
    one of the following organisms would you MOST probably have
    isolated?
    (A) Streptococcus pyogenes
    (B) Staphylococcus aureus
    (C) Staphylococcus epidermidis
    (D) Streptococcus pneumoniae
A

(A) Streptococcus pyogenes

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9
Q
  1. Which one of the following host defense mechanisms is the
    MOST important for preventing dysentery caused by Salmonella?
    (A) Gastric acid
    (B) Salivary enzymes
    (C) Normal flora of the mouth
    (D) Alpha interfero
A

(A) Gastric acid

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10
Q 
66. Five hours after eating reheated rice at a restaurant, a 24-yearold woman and her husband both developed nausea, vomiting, and diarrhea. Which one of the following organisms is the 
MOST likely to be involved?
(A) Clostridium perfringens
(B) Enterotoxigenic Escherichia coli
(C) Bacillus cereus
(D) Salmonella typhi
A

(C) Bacillus cereus

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11
Q 
67. Which one of the following bacteria has the LOWEST 50% 
infectious dose (ID50)?
(A) Shigella sonnei
(B) Vibrio cholerae
(C) Salmonella typhi
(D) Campylobacter jejuni
A

(A) Shigella sonnei

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12
Q 
68. For which one of the following enteric illnesses is a chronic carrier state MOST likely to develop?
(A) Campylobacter enterocolitis
(B) Shigella enterocolitis
(C) Cholera
(D) Typhoid fever
A

(D) Typhoid fever

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13
Q 
69. Which one of the following zoonotic illnesses has NO arthropod 
vector?
(A) Plague
(B) Lyme disease
(C) Brucellosis
(D) Epidemic typhus
A

(C) Brucellosis

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14
Q
  1. Which one of the following statements MOST accurately depicts
    the ability of the organism to be cultured in the laboratory?
    (A) Treponema pallidum from a chancre can be grown on a special artificial medium supplemented with cholesterol.
    (B) Mycobacterium leprae can be grown in the armadillo and the
    mouse footpad but not on any artificial media.
    (C) Mycobacterium tuberculosis can be grown on enriched artificial media and produces visible colonies in 48 to 96 hours.
    (D) Atypical mycobacteria are found widely in soil and water but
    cannot be cultured on artificial media in the laboratory.
A

(B) Mycobacterium leprae can be grown in the armadillo and the
mouse footpad but not on any artificial media.

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15
Q
  1. Each of the following statements concerning chlamydiae is correct EXCEPT:
    (A) Chlamydiae are strict intracellular parasites because they
    cannot synthesize sufficient adenosine triphosphate (ATP).
    (B) Chlamydiae possess both DNA and RNA and are bounded
    by a cell wall.
    (C) Chlamydia trachomatis has multiple serotypes that can cause
    different diseases.
    (D) Most chlamydiae are transmitted by arthropods.
A

(D) Most chlamydiae are transmitted by arthropods.

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16
Q
  1. For which one of the following bacterial vaccines are toxic side
    effects an important concern?
    (A) The vaccine containing pneumococcal polysaccharide
    (B) The vaccine containing killed Bordetella pertussis
    (C) The vaccine containing tetanus toxoid
    (D) The vaccine containing diphtheria toxoid
A

(B) The vaccine containing killed Bordetella pertussis

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17
Q
  1. A 65-year-old man develops dysuria and hematuria. A Gram
    stain of a urine sample shows gram-negative rods. Culture of
    the urine on EMB agar reveals lactose-negative colonies without evidence of swarming motility. Which one of the following
    organisms is MOST likely to be the cause of his urinary tract
    infection?
    (A) Enterococcus faecalis
    (B) Pseudomonas aeruginosa
    (C) Proteus vulgaris
    (D) Escherichia coli
A

(B) Pseudomonas aeruginosa

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18
Q 
77. A 25-year-old man complains of a urethral discharge. You perform a Gram stain on a specimen of the discharge and see neutrophils but no bacteria. Of the organisms listed, the one MOST 
likely to cause the discharge is:
(A) Treponema pallidum
(B) Chlamydia trachomatis
(C) Candida albicans
(D) Coxiella burnetii
A

(B) Chlamydia trachomatis

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19
Q
  1. Your patient has a brain abscess that was detected 1 month after
    a dental extraction. Which one of the following organisms is
    MOST likely to be involved?
    (A) Anaerobic streptococci
    (B) Mycobacterium smegmatis
    (C) Lactobacillus acidophilus
    (D) Mycoplasma pneumoniae
A

(A) Anaerobic streptococci

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20
Q
  1. The MOST important contribution of the capsule of Streptococcus
    pneumoniae to virulence is:
    (A) To prevent dehydration of the organisms on mucosal
    surfaces
    (B) To retard phagocytosis by polymorphonuclear leukocytes
    (C) To inhibit polymorphonuclear leukocyte chemotaxis
    (D) To accelerate tissue invasion by its collagenase-like activity
A

(B) To retard phagocytosis by polymorphonuclear leukocytes

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21
Q
  1. The MOST important way the host counteracts the function of
    the pneumococcal polysaccharide capsule is via:
    (A) T lymphocytes sensitized to polysaccharide antigens
    (B) Polysaccharide-degrading enzymes
    (C) Anticapsular antibody
    (D) Activated macrophages
A

(C) Anticapsular antibody

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22
Q
  1. The pathogenesis of which one of the following organisms is
    MOST likely to involve invasion of the intestinal mucosa?
    (A) Vibrio cholerae
    (B) Shigella sonnei
    (C) Enterotoxigenic Escherichia coli
    (D) Clostridium botulinum
A

(B) Shigella sonnei

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23
Q 
83. Which one of the following organisms that infects the gastrointestinal tract is the MOST frequent cause of bacteremia?
(A) Shigella flexneri
(B) Campylobacter jejuni
(C) Vibrio cholerae
(D) Salmonella typhi
A

(D) Salmonella typhi

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24
Q
  1. Each of the following statements concerning Treponema is correct EXCEPT:
    (A) Treponema pallidum produces an exotoxin that stimulates
    adenylate cyclase.
    (B) Treponema pallidum cannot be grown on conventional laboratory media.
    (C) Treponemes are members of the normal flora of the human
    oropharynx.
    (D) Patients infected with T. pallidum produce antibodies that
    react with beef heart cardiolipin.
A

(A) Treponema pallidum produces an exotoxin that stimulates

adenylate cyclase.

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25
Q
  1. A 70-year-old man is found to have a hard mass in his prostate, which is suspected to be a carcinoma. Twenty-four hours
    after surgical removal of the mass, he develops fever to 39°C and
    has several shaking chills. Of the organisms listed, which one is
    LEAST likely to be involved?
    (A) Escherichia coli
    (B) Enterococcus faecalis
    (C) Klebsiella pneumoniae
    (D) Legionella pneumophila
A

(D) Legionella pneumophila

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26
Q 
93. The pathogenesis of which one of the following diseases does 
NOT involve an exotoxin?
(A) Scarlet fever
(B) Typhoid fever
(C) Toxic shock syndrome
(D) Botulism
A

(B) Typhoid fever

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27
Q 
94. Regarding the effect of benzylpenicillin (penicillin G) on bacteria, which one of the following organisms is LEAST likely to be 
resistant?
(A) Staphylococcus aureus
(B) Enterococcus faecalis
(C) Streptococcus pyogenes
(D) Neisseria gonorrhoeae
A

(C) Streptococcus pyogenes

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28
Q
  1. Which one of the following organisms is MOST likely to be the
    cause of pneumonia in an immunocompetent young adult?
    (A) Nocardia asteroides
    (B) Serratia marcescens
    (C) Mycoplasma pneumoniae
    (D) Legionella pneumophila
A

(C) Mycoplasma pneumoniae

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29
Q
  1. Each of the following statements concerning chlamydial genital
    tract infections is correct EXCEPT:
    (A) Infection can be diagnosed by finding antichlamydial antibody in a serum specimen.
    (B) Infection can persist after administration of penicillin.
    (C) Symptomatic infections can be associated with urethral or
    cervical discharge containing many polymorphonuclear
    leukocytes.
    (D) There is no vaccine against these infections.
A

(A) Infection can be diagnosed by finding antichlamydial antibody in a serum specimen.

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30
Q 
97. Which one of the following illnesses is NOT a zoonosis?
(A) Typhoid fever
(B) Q fever
(C) Tularemia
(D) Rocky Mountain spotted fever
A

(A) Typhoid fever

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31
Q
  1. Which one of the following is NOT an important characteristic
    of either Neisseria gonorrhoeae or Neisseria meningitidis?
    (A) Polysaccharide capsule
    (B) IgA protease
    (C) M protein
    (D) Pili
A

(C) M protein

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32
Q
  1. Which one of the following is NOT an important characteristic
    of Streptococcus pyogenes?
    (A) Protein A
    (B) M protein
    (C) β-Hemolysin
    (D) Polysaccharide group-specific substance
A

(A) Protein A

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33
Q
  1. Each of the following is associated with the Lancefield group B
    streptococci (S. agalactiae) EXCEPT:
    (A) Pyoderma (impetigo)
    (B) Vaginal carriage in 5% to 25% of normal women of childbearing age
    (C) Neonatal sepsis and meningitis
    (D) β-Hemolysis
A

(A) Pyoderma (impetigo)

34
Q 
102. Three organisms, Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae, cause the vast majority of cases of bacterial meningitis. What is the MOST important pathogenic 
component they share?
(A) Protein A
(B) Capsule
(C) Endotoxin
(D) β-Lactamase
A

(B) Capsule

35
Q 
103. Diarrhea caused by which one of the following agents is characterized by the presence of fecal leukocytes?
(A) Campylobacter jejuni
(B) Rotavirus
(C) Clostridium perfringens
(D) Enterotoxigenic Escherichia coli
A

(A) Campylobacter jejuni

36
Q
  1. Each of the following statements concerning Chlamydia
    trachomatis is correct EXCEPT:
    (A) It is an important cause of nongonococcal urethritis.
    (B) It is the cause of lymphogranuloma venereum.
    (C) It is an important cause of subacute bacterial endocarditis.
    (D) It is an important cause of conjunctivitis.
A

(C) It is an important cause of subacute bacterial endocarditis.

37
Q 
106. Which one of the following types of organisms is NOT an obligate intracellular parasite and therefore can replicate on bacteriologic media?
(A) Chlamydia
(B) Mycoplasma
(C) Adenovirus
(D) Rickettsia
A

(B) Mycoplasma

38
Q
  1. Tissue-degrading enzymes play an important role in the pathogenesis of several bacteria. Which one of the following is NOT
    involved in tissue or cell damage?
    (A) Lecithinase of Clostridium perfringens
    (B) Hyaluronidase of Streptococcus pyogenes
    (C) M protein of Streptococcus pneumoniae
    (D) Leukocidin of Staphylococcus aureus
A

(C) M protein of Streptococcus pneumoniae

39
Q
  1. The soil is the natural habitat for certain microorganisms of
    medical importance. Which one of the following is LEAST likely
    to reside there?
    (A) Clostridium tetani
    (B) Mycobacterium avium-intracellulare
    (C) Bacillus anthracis
    (D) Chlamydia trachomatis
A

(D) Chlamydia trachomatis

40
Q 
109. Which one of the following organisms is the MOST frequent 
bacterial cause of pharyngitis?
(A) Staphylococcus aureus
(B) Streptococcus pneumoniae
(C) Streptococcus pyogenes
(D) Neisseria meningitidis
A

(C) Streptococcus pyogenes

41
Q
  1. Several pathogens are transmitted either during gestation or at
    birth. Which one of the following is LEAST likely to be transmitted at these times?
    (A) Haemophilus influenzae
    (B) Treponema pallidum
    (C) Neisseria gonorrhoeae
    (D) Chlamydia trachomatis
A

(A) Haemophilus influenzae

42
Q
  1. Each of the following statements concerning the VDRL test for
    syphilis is correct EXCEPT:
    (A) The antigen is composed of inactivated Treponema
    pallidum.
    (B) The test is usually positive in secondary syphilis.
    (C) False-positive results are more frequent than with the fluorescent treponemal antibody-absorbed (FTA-ABS) test.
    (D) The antibody titer declines with appropriate therapy.
A

(A) The antigen is composed of inactivated Treponema

pallidum.

43
Q
  1. Each of the following statements concerning the fluorescent
    treponemal antibody-absorbed (FTA-ABS) test for syphilis is
    correct EXCEPT:
    (A) The test is specific for Treponema pallidum.
    (B) The patient’s serum is absorbed with saprophytic
    treponemes.
    (C) Once positive, the test remains so despite appropriate
    therapy.
    (D) The test is rarely positive in primary syphilis.
A

(D) The test is rarely positive in primary syphilis.

44
Q
  1. Each of the following statements concerning enterotoxins is correct EXCEPT:
    (A) Enterotoxins typically cause bloody diarrhea with leukocytes
    in the stool.
    (B) Staphylococcus aureus produces an enterotoxin that causes
    vomiting and diarrhea.
    (C) Vibrio cholerae causes cholera by producing an enterotoxin
    that increases adenylate cyclase activity within the enterocyte.
    (D) Escherichia coli enterotoxin mediates ADP-ribosylation of a
    G protein.
A

(A) Enterotoxins typically cause bloody diarrhea with leukocytes
in the stool.

45
Q
  1. Each of the following statements concerning plague is correct
    EXCEPT:
    (A) Plague is caused by a gram-negative rod that can be cultured
    on blood agar.
    (B) Plague is transmitted from the animal reservoir to humans
    by flea bite.
    (C) The main reservoirs in nature are small rodents.
    (D) Plague is of concern in many underdeveloped countries but
    has not occurred in the United States since 1968.
A

(D) Plague is of concern in many underdeveloped countries but
has not occurred in the United States since 1968.

46
Q
  1. Which one of the following statements concerning the organisms that cause brucellosis is CORRECT?
    (A) Brucellae are transmitted primarily by tick bite.
    (B) The principal reservoirs of Brucellae are small rodents.
    (C) Brucellae infect reticuloendothelial cells in the liver, spleen,
    and bone marrow.
    (D) Brucellae are obligate intracellular parasites that are usually
    identified by growth in human cell culture.
A

(C) Brucellae infect reticuloendothelial cells in the liver, spleen,
and bone marrow

47
Q 
120. Which one of the following organisms causes diarrhea by producing an enterotoxin that increases adenylate cyclase activity 
within enterocytes?
(A) Escherichia coli
(B) Bacteroides fragilis
(C) Staphylococcus aureus
(D) Enterococcus faecalis
A

(A) Escherichia coli

48
Q
  1. Each of the following statements concerning gonorrhea is correct EXCEPT:
    (A) Infection in men is more frequently symptomatic than in
    women.
    (B) A presumptive diagnosis can be made by finding gramnegative kidney bean-shaped diplococci within neutrophils
    in a urethral discharge.
    (C) The definitive diagnosis can be made by detecting antibodies
    to Neisseria gonorrhoeae in the patient’s serum.
    (D) Gonococcal conjunctivitis of the newborn rarely occurs in
    the United States, because silver nitrate or erythromycin is
    commonly used as prophylaxis.
A

(C) The definitive diagnosis can be made by detecting antibodies
to Neisseria gonorrhoeae in the patient’s serum.

49
Q
  1. Each of the following statements concerning spirochetes is correct EXCEPT:
    (A) Species of Treponema are part of the normal flora of the
    mouth.
    (B) Species of Borrelia cause a tick-borne disease called relapsing
    fever.
    (C) The species of Leptospira that cause leptospirosis grow primarily in humans and are usually transmitted by human-tohuman contact.
    (D) Species of Treponema cause syphilis and yaws.
A

(C) The species of Leptospira that cause leptospirosis grow primarily in humans and are usually transmitted by human-tohuman contact.

50
Q
  1. Each of the following statements concerning Mycobacterium
    tuberculosis is correct EXCEPT:
    (A) Some strains of M. tuberculosis isolated from patients exhibit
    multiple drug resistance (i.e., they are resistant to both isoniazid and rifampin).
    (B) Mycobacterium tuberculosis contains a small amount of lipid
    in its cell wall and therefore stains poorly with the Gram
    stain.
    (C) Mycobacterium tuberculosis grows slowly, often requiring 3
    to 6 weeks before colonies appear.
    (D) The antigen in the tuberculin skin test is a protein extracted
    from the organism.
A

(B) Mycobacterium tuberculosis contains a small amount of lipid
in its cell wall and therefore stains poorly with the Gram
stain.

51
Q
  1. Each of the following statements concerning neisseriae is correct EXCEPT:
    (A) They are gram-negative diplococci.
    (B) They produce IgA protease as a virulence factor.
    (C) They are oxidase-positive.
    (D) They grow best under anaerobic conditions.
A

(D) They grow best under anaerobic conditions.

52
Q
  1. Which one of the following statements concerning Legionella
    pneumophila is CORRECT?
    (A) It is part of the normal flora of the colon.
    (B) It cannot be grown on laboratory media.
    (C) It does not have a cell wall.
    (D) It causes atypical pneumonia, especially in those with
    reduced cell-mediated immunity.
A

(D) It causes atypical pneumonia, especially in those with

reduced cell-mediated immunity.

53
Q
  1. Each of the following statements concerning infection with
    Chlamydia psittaci is correct EXCEPT:
    (A) Chylamydia psittaci can be isolated by growth in cell culture
    and will not grow in blood agar.
    (B) The organism appears purple in Gram-stained smears of
    sputum.
    (C) The infection is more readily diagnosed by serologic tests
    than by isolation of the organism.
    (D) The infection is more commonly acquired from a nonhuman
    source than from another human.
A

(B) The organism appears purple in Gram-stained smears of

sputum.

54
Q 
132. Ticks are vectors for the transmission of each of the following 
diseases EXCEPT:
(A) Rocky Mountain spotted fever
(B) Epidemic typhus
(C) Tularemia
(D) Lyme disease
A

(B) Epidemic typhus

55
Q
  1. Each of the following statements concerning pneumonia caused
    by Mycoplasma pneumoniae is correct EXCEPT:
    (A) Pneumonia caused by M. pneumoniae is associated with a
    rise in the titer of cold agglutinins.
    (B) Pneumonia caused by M. pneumoniae occurs primarily in
    immunocompetent individuals.
    (C) Pneumonia caused by M. pneumoniae is an “atypical”
    pneumonia.
    (D) Mycoplasma pneumoniae cannot be cultured in vitro because
    it has no cell wall.
A

(D) Mycoplasma pneumoniae cannot be cultured in vitro because
it has no cell wall.

56
Q
  1. Each of the following statements concerning Neisseria
    meningitidis is correct EXCEPT:
    (A) It is an oxidase-positive, gram-negative diplococcus.
    (B) It contains endotoxin in its cell wall.
    (C) It produces an exotoxin that stimulates adenylate cyclase.
    (D) It has a polysaccharide capsule that is antiphagocytic.
A

(C) It produces an exotoxin that stimulates adenylate cyclase.

57
Q
  1. Each of the following statements concerning Mycobacterium
    leprae is correct EXCEPT:
    (A) In lepromatous leprosy, large numbers of organisms are usually seen in acid-fast–stained smears.
    (B) The organism will grow on bacteriologic media in 3 to 6 weeks.
    (C) Prolonged therapy (9 months or longer) is required to prevent recurrence.
    (D) Loss of sensation due to nerve damage is often seen in leprosy.
A

(B) The organism will grow on bacteriologic media in 3 to 6 weeks.

58
Q
  1. An outbreak of sepsis caused by Staphylococcus aureus has
    occurred in the newborn nursery. You are called upon to investigate. According to your knowledge of the normal flora, what is
    the MOST likely source of the organism?
    (A) Colon
    (B) Nose
    (C) Throat
    (D) Vagina
A

(B) Nose

59
Q
  1. A 50-year-old homeless alcoholic has a fever and is coughing up
    1 cup of green, foul-smelling sputum per day. You suspect that
    he may have a lung abscess. Which one of the following pairs of
    organisms is MOST likely to be the cause?
    (A) Listeria monocytogenes and Legionella pneumophila
    (B) Nocardia asteroides and Mycoplasma pneumoniae
    (C) Fusobacterium nucleatum and Peptostreptococcus
    intermedius
    (D) Clostridium perfringens and Chlamydia psittaci
A

(C) Fusobacterium nucleatum and Peptostreptococcus

intermedius

60
Q
  1. The coagulase test, in which the bacteria cause plasma to clot, is
    used to distinguish:
    (A) Streptococcus pyogenes from Enterococcus faecalis
    (B) Streptococcus pyogenes from Staphylococcus aureus
    (C) Staphylococcus aureus from Staphylococcus epidermidis
    (D) Staphylococcus epidermidis from Neisseria meningitidis
A

(C) Staphylococcus aureus from Staphylococcus epidermidis

61
Q
  1. Which one of the following is a virulence factor for Staphylococcus
    aureus?
    (A) A heat-labile toxin that inhibits glycine release at the internuncial neuron
    (B) An oxygen-labile hemolysin
    (C) Resistance to novobiocin
    (D) Protein A that binds to the Fc portion of IgG
A

(D) Protein A that binds to the Fc portion of IgG

62
Q
  1. The MOST important protective function of the antibody stimulated by tetanus immunization is:
    (A) To opsonize the pathogen (Clostridium tetani)
    (B) To prevent growth of the pathogen
    (C) To prevent adherence of the pathogen
    (D) To neutralize the toxin of the pathogen
A

(D) To neutralize the toxin of the pathogen

63
Q 
70. Which one of the following organisms principally infects vascular endothelial cells and as a result often causes a petechial rash?
(A) Salmonella typhi
(B) Rickettsia rickettsii
(C) Haemophilus influenzae
(D) Coxiella burnetii
A

(B) Rickettsia rickettsii

64
Q
  1. Each of the following statements concerning Staphylococcus
    aureus is correct EXCEPT:
    (A) Gram-positive cocci in grapelike clusters are seen on Gramstained smear.
    (B) The coagulase test is positive.
    (C) Treatment should include a β-lactamase-resistant penicillin.
    D) Endotoxin is an important pathogenetic factor
A

D) Endotoxin is an important pathogenetic factor

65
Q
  1. Your patient is a 70-year-old man who underwent bowel surgery
    for colon cancer 3 days ago. He now has a fever and abdominal
    pain. You are concerned that he may have peritonitis. Which
    one of the following pairs of organisms is MOST likely to be the
    cause?
    (A) Bacteroides fragilis and Klebsiella pneumoniae
    (B) Bordetella pertussis and Salmonella enteritidis
    (C) Actinomyces israelii and Campylobacter jejuni
    (D) Clostridium botulinum and Shigella dysenteriae
A

(A) Bacteroides fragilis and Klebsiella pneumoniae

66
Q
  1. Two hours after a delicious Thanksgiving dinner of barley soup,
    roast turkey, stuffing, sweet potato, green beans, cranberry sauce,
    and pumpkin pie topped with whipped cream, the Smith family
    of four experience vomiting and diarrhea. Which one of the following organisms is MOST likely to cause these symptoms?
    (A) Shigella flexneri
    (B) Campylobacter jejuni
    (C) Staphylococcus aureus
    (D) Salmonella enteritidis
A

(C) Staphylococcus aureus

67
Q
  1. Each of the following statements concerning clostridia is correct
    EXCEPT:
    (A) Pathogenic clostridia are found both in the soil and in the
    normal flora of the colon.
    (B) Antibiotic-associated (pseudomembranous) colitis is due to
    a toxin produced by Clostridium difficile.
    (C) Anaerobic conditions at the wound site are not required to
    cause tetanus, because spores will form in the presence of
    oxygen.
    (D) Botulism, which is caused by ingesting preformed toxin, can
    be prevented by boiling food prior to eating.
A

(C) Anaerobic conditions at the wound site are not required to
cause tetanus, because spores will form in the presence of
oxygen.

68
Q
  1. Each of the following statements concerning Bacteroides fragilis
    is correct EXCEPT:
    (A) Bacteroides fragilis is a gram-negative rod that is part of the
    normal flora of the colon.
    (B) Bacteroides fragilis forms endospores, which allow it to survive in the soil.
    (C) The capsule of B. fragilis is an important virulence factor.
    (D) Bacteroides fragilis infections are characterized by foulsmelling pus.
A

(B) Bacteroides fragilis forms endospores, which allow it to survive in the soil.

69
Q
  1. Each of the following statements concerning staphylococci is
    correct EXCEPT:
    (A) Staphylococcus aureus is differentiated from Staphylococcus
    epidermidis by the production of coagulase.
    (B) Staphylococcus aureus infections are often associated with
    abscess formation.
    (C) The majority of clinical isolates of S. aureus produce penicillinase; therefore, penicillin G should not be used for antibiotic therapy for S. aureus infections.
    (D) Scalded skin syndrome caused by S. aureus is due to enzymatic degradation of epidermal desmosomes by catal
A

(D) Scalded skin syndrome caused by S. aureus is due to enzymatic degradation of epidermal desmosomes by catal

70
Q
  1. Five days ago, a 65-year-old woman with a lower urinary tract
    infection began taking ampicillin. She now has a fever and
    severe diarrhea. Of the organisms listed, which one is MOST
    likely to be the cause of the diarrhea?
    (A) Clostridium difficile
    (B) Bacteroides fragilis
    (C) Proteus mirabilis
    (D) Bordetella pertussis
A

(A) Clostridium difficile

71
Q
  1. Which one of the following is NOT a characteristic of the
    Staphylococcus associated with toxic shock syndrome?
    (A) Release of a superantigen
    (B) Coagulase production
    (C) Appearance of the organism in grapelike clusters on Gramstained smear
    (D) Catalase-negative reaction
A

(D) Catalase-negative reaction

72
Q
  1. Each of the following statements concerning Actinomyces and
    Nocardia is correct EXCEPT:
    (A) Actinomysis israelii is an anaerobic rod found as part of the
    normal flora in the mouth.
    (B) Both Actinomyces and Nocardia are branching, filamentous
    rods.
    (C) Nocardia asteroides causes infections primarily in immunocompromised patients.
    (D) Infections are usually diagnosed by detecting a significant
    rise in antibody titer.
A

(D) Infections are usually diagnosed by detecting a significant
rise in antibody titer.

73
Q
  1. Each of the following statements concerning exotoxins is correct
    EXCEPT:
    (A) Some strains of Escherichia coli produce an enterotoxin that
    causes diarrhea.
    (B) Cholera toxin acts by stimulating adenylate cyclase.
    (C) Diphtheria is caused by an exotoxin that inhibits protein
    synthesis by inactivating an elongation factor.
    (D) Botulism is caused by a toxin that hydrolyzes lecithin
    (lecithinase), thereby destroying nerve cells.
A

(D) Botulism is caused by a toxin that hydrolyzes lecithin

(lecithinase), thereby destroying nerve cells.

74
Q
  1. Each of the following statements concerning Corynebacterium
    diphtheriae is correct EXCEPT:
    (A) Corynebacterium diphtheriae is a gram-positive rod that does
    not form spores.
    (B) Toxin production is dependent on the organism’s being
    lysogenized by a bacteriophage.
    (C) Diphtheria toxoid should not be given to children younger
    than 3 years because the incidence of complications is too
    high.
    (D) Antitoxin should be used to treat patients with diphtheria.
A

(C) Diphtheria toxoid should not be given to children younger
than 3 years because the incidence of complications is too
high.

75
Q
  1. Each of the following statements concerning epidemic typhus is
    correct EXCEPT:
    (A) The disease is characterized by a rash.
    (B) The Weil-Felix test can aid in diagnosis of the disease.
    (C) The disease is caused by a Rickettsia.
    (D) The causative organism is transmitted from rodents to
    humans by a tick.
A

(D) The causative organism is transmitted from rodents to

humans by a tick.

76
Q
  1. Each of the following statements concerning Rocky Mountain
    spotted fever is correct EXCEPT:
    (A) The causative organism forms β-hemolytic colonies on blood
    agar.
    (B) Headache, fever, and rash are characteristic features of the
    disease.
    (C) The disease occurs primarily east of the Mississippi.
    (D) The disease is caused by a Rickettsia.
A

(A) The causative organism forms β-hemolytic colonies on blood
agar.

77
Q
  1. Each of the following statements concerning Clostridium
    perfringens is correct EXCEPT:
    (A) It causes gas gangrene.
    (B) It causes food poisoning.
    (C) It produces an exotoxin that degrades lecithin and causes
    necrosis and hemolysis.
    (D) It is a gram-negative rod that does not ferment lactose.
A

(D) It is a gram-negative rod that does not ferment lactose.

78
Q
  1. Each of the following statements concerning Clostridium tetani
    is correct EXCEPT:
    (A) It is a gram-positive, spore-forming rod.
    (B) Pathogenesis is due to the production of an exotoxin that
    blocks inhibitory neurotransmitters.
    (C) It is a facultative organism; it will grow on a blood agar plate
    in the presence of room air.
    (D) Its natural habitat is primarily the soil.
A

(C) It is a facultative organism; it will grow on a blood agar plate
in the presence of room air.

79
Q
  1. Which one of the following statements concerning immunization against diseases caused by clostridia is CORRECT?
    (A) Antitoxin against tetanus protects against botulism as well,
    because the two toxins share antigenic sites.
    (B) Vaccines containing alpha toxin (lecithinase) are effective in
    protecting against gas gangrene.
    (C) The toxoid vaccine against Clostridium difficile infection
    should be administered to immunocompromised patients.
    (D) Immunization with tetanus toxoid induces effective protection against tetanus toxin.
A

(D) Immunization with tetanus toxoid induces effective protection against tetanus toxin.

80
Q
  1. Each of the following statements concerning wound infections
    caused by Clostridium perfringens is correct EXCEPT:
    (A) An exotoxin plays a role in pathogenesis.
    (B) Gram-positive rods are found in the exudate.
    (C) The organism grows only in human cell culture.
    (D) Anaerobic culture of the wound site should be ordered.
A

(C) The organism grows only in human cell culture.

81
Q
  1. Each of the following statements concerning Q fever is correct
    EXCEPT:
    (A) Rash is a prominent feature.
    (B) It is transmitted by respiratory aerosol.
    (C) Farm animals are an important reservoir.
    (D) It is caused by Coxiella burnetii.
A

(A) Rash is a prominent feature.

microbiology (8 decks)

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